This application relates to distributed generation control for microgrids.
The increasing penetration of distributed energy sources (DER) brings about the concept of microgrid (MG), in which distributed generation (DG) units and load are integrated in a low voltage (LV) network to enhance the reliability of the electric power systems. Integration of individual DGs not only benefits utilities and customers economically but also guarantees the continuity of the electricity supply under emergency conditions. Various types of DGs exist in a MG, including micro-turbine, photovoltaic (PV) system, fuel cell, battery storage, etc. These DGs are interfaced to the MG either through power electronic converters or through ac rotating machines. Compared to conventional rotating machines, DGs has the advantages of faster control capabilities with higher degree of flexibility. However, control of DGs remains a challenging area to explore, since they may bring as many problems as they may solve.
An MG should work under the grid-tied mode and the islanded mode. Under normal operating conditions, a MG is connected to a medium voltage network, either absorbing power from or injecting power into the main grid. Under the emergency mode, the MG is disconnected from the main grid and works autonomously, in a similar way to physical islands. The smooth transition between these two modes is of vital importance to realize the claimed benefits of MG.